A minister in your local area begins to attack you from the pulpit about a certain doctrine you teach. What is your response to this minister?
Your question doesn’t make it absolutely clear whether the preacher is attacking you personally, or just attacking the teaching of the doctrine. If his attacks are against you personally there is not much you can do although he is in the wrong. I think that would be covered under Matthew 5:1. “Blessed are ye, when men shall revile you, and persecute you, and shall say all manner of evil against you falsely, for my sake.” Likewise, 1 Peter 4:15-16 might apply. “But let none of you suffer as a murderer, or as a thief, or as an evildoer, or as a busybody in other men's matters. Yet if any man suffer as a Christian, let him not be ashamed; but let him glorify God on this behalf.”
If he is attacking the doctrine itself, then you have two valid responses. First would be to examine the doctrine in the light of what he says and in the light of the Bible, to see if it is a doctrine truly taught by the Bible. (Historically, many doctrines have developed that have no scriptural basis: abolition of slavery, perpetual virginity of Mary, dancing or cards or “mixed swimming” are sins, etc.) “These were more noble than those in Thessalonica, in that they received the word with all readiness of mind, and searched the scriptures daily, whether those things were so.” (Acts 17:11)
The second response would depend on the first. If you cannot find the doctrine in scripture then you should drop the doctrine. If you can support it by scripture, then all you can do is defend it as publicly as necessary, always using the scripture to show the validity of the doctrine. If you find that he and you actually agree, but are using different words for the same thing, then you should get with him and see if both of you can’t agree on using the scriptural language when teaching the doctrine.